Bobbin thread replenishing mechanism for sewing machines

ABSTRACT

A lockstitch sewing mechanism in which needle thread may be directed to the bobbin for bobbin thread replenishment by a novel route beneath the level of the path of the loop seizing beak of the loop taker together with means for introducing and snubbing the thread on a plain cylindrical bobbin hub of small diameter whereby an appreciable increase in bobbin thread capacity is obtained.

United States Patent Ketterer [451 Sept. 26, 1972 [54] BOBBIN THREADREPLENISHING MECHANISM FOR SEWING MACHINES [72] Inventor: Stanley .1.Ketterer, Jamesburg, NJ.

173] Assignec: The Singer Company, New York,

[22] Filed: April 23, 1971 [21] Appl. No.: 136,929

[52] U.S.Cl ..112/184, 112/186 [51 I Int. Cl. ..D05b 57/14, D05b 59/00[581 Field of Search ..112/184, 181, 182, 183,186,

[56] References Cited UNITED STATES PATENTS Johnson ..112/184 X3,490,402 1/1970 Ketterer ..1 12/186 X Primary Examiner-H. HamptonHunter Attorney-Marsha J Breen, Chester A. Williams, Jr. and Robert E.Smith ABSTRACT A lockstitch sewing mechanism in which needle thread maybe directed to the bobbin for bobbin thread replenishment by a novelroute beneath the level of the path of the loop seizing beak of the looptaker together with means for introducing and snubbing the thread on aplain cylindrical bobbin hub of small diameter whereby an appreciableincrease in bobbin thread capacity is obtained.

5 Claims, 12 Drawing Figures PATENTEDSP26 1972 SHEET 1 [IF 4 INVENTORStanley J. Ketterer BY fiwflflwz ATTORNEY PAIENTED SEP 2 6 I972 SHEET 2OF 4 INVENTOR. Stanley J. Ketterer WML;

ATTORNEY mimsussrzsmz H 3,693,566

SHEET 3 [1F 4 INVENTOR. Stanley J. Ketterer PATENTEU I97? 3.693, 566

INVENTOR. Stanley J. Ketterer WITNESS: M

BOBBIN THREAD REPLENISIIING MECHANISM FOR SEWING'MACIIINES BACKGROUND OFTHE INVENTION Mechanisms heretofore known for replenishing thread on abobbin in place in a loop taker while the stitch forminginstrumentalities remainoperatively associated as required for sewinghave required that the hub of the bobbin be formed with a sufficientlylarge diameter so that the thread will always be wound at a rate fastenough to prevent slack at loop seizure time. In order to insure againstthread breakage which would occur if the needle thread were to beseizeda second time by the loop taker during bobbin winding, the bobbinthread capacity of any given size loop taker heretofore had to besacrificed.

SUMMARY OF THE INVENTION In the present invention, thread I from asewing machine needle after the first seizure by the loop taker isintroduced into the bobbin by a novel route to initiate replenishment ofthe bobbin thread. By directing v the replenishment thread from theneedle to the bobbin so as to extend on the opposite side of the planecontaining the path of the loop seizing beak from the nee- "dle threadsupply, a loop of needle thread will not be formed in the path of theloop taker beak after the initial needle thread loop has been seized.Regardless of the slack in the thread, the needle thread will not betalities.

This invention also provides a bobbin thread replenishing mechanism forlockstitch sewing machines inwhich the bobbin thread is subjected to theaction of a spring tensioning device so that during sewing, uniformbobbin thread tension will be imposed irrespective of the quantity ofthread wound on the bobbin. This invention, moreover, provides for anovel and effective mechanism for selectively rendering a sewing machineloop taker effective either to wind replenishment thread on the bobbintherein or to form lockstitches.

With the above and additional objects and advantages in view, as willhereinafter appear, this invention will now be described in detail withreference to the accompanying drawings of a preferred embodiment inwhich:

FIG. 1 represents a vertical cross-sectional view taken lengthwise alonga sewing machine bed and through the axis of rotation of a rotary hookconstructed in accordance with this invention,

FIG. 2 represents a vertical cross sectional view of a prior art rotaryhook shown as the loop taker moves past the needle while thread from thesewing machine needle is being replenished on a bobbin in the hook,

FIG. 3 represents a vertical cross-sectional view of the rotary hook ofthis invention shown as the loop taker moves past the needle whilethread from the sewing machine needle is being replenished on a bobbinin the hook,

FIG. 4 is a disassembled perspective view of the rotary hook of thisinvention including the mechanism for constraining the bobbin case inplace on the hook and the mechanism for replenishing bobbin thread,

FIG. 5 is a top plan view of the rotary hook of FIGS. 1 and 4 with themechanism for replenishing bobbin thread shown in solid lines inoperative condition for bobbin winding and with the hook shown in aposition immediately after seizure of a thread loop from the needle,

FIG. 6 is a top plan view similar to FIG. 5 but showing the hook in aposition in which the thread loop seized thereby is being deflected tothe action of the bobbin thread tensioning spring,

FIG. 7 is a top plan view similar to FIG. 5 but showing a position ofparts in which the thread loop is about to be shed from the hook beak,

FIG. 8 is a top plan view similar to FIG. 5 but showing a position inwhich the thread loop is entering the bobbin flange slot,

FIG. 9 is an elevational view of the bobbin case illustrating the bobbinthread tensioning spring means and showing the thread as it is locatedwith respect to the spring means in the position of parts as shown inFIG. 8,

FIG. 10 is a perspective view of a fragment of the bobbin case, bobbinthread tensioning spring means, thread replenishing control lever, andhook beak and including a representation of the thread being directed tothe bobbin thread tensioning spring during bobbin replenishment,

FIG. 11 is a perspective view similar to FIG. 10 but showing a needlethread loop by-passing the bobbin thread tensioning spring duringsewing, and

FIG. 12 is a cross-sectional view through the rotary hook takensubstantially along line l2-12 of FIG. 8 but showing the position of thethread after several rotations of the bobbin at the start of threadreplenishment and indicating the manner in which the beginning end ofthread is severed.

The loop taker illustrated in the drawings is adapted for use with asewing machine such as is disclosed in the U.S. Pat. No. 2,862,468, Dec.2, 1958, ofR. E. Johnson which is incorporated herein by reference. Theabovecited patent may be referred to for disclosure of all of the sewingmachine mechanism save for the loop taker and mechanism directly relatedwith the loop taker such as the bobbin thread replenishing mechanism.

In the drawings, 20 denotes the bed of a sewing machine frame' carryinga bushing 21 in which a bed shaft 22 is journalled. The bed 20 is formedwith an upwardly open loop taker accommodating cavity 23 closed by aslide cover plate 24 and by a throat plate 25. Rotatable in a bushing 26carried in the bed is a hollow loop taker shaft 27 which is attached asby welding or the like to the underside of a loop taker indicatedgenerally at 28 which is disposed in the cavity 23.

The loop taker disclosed in the drawingsis a rotary book which isimparted turning movement in one direction during operation of thesewing machine by a bevel gear 29 made fast on the loop taker shaft by aset screw 30 and in mesh with a bevel gear 31 secured by a set screw 32to the bed shaft. Preferably, the rotary hook partakes of tworevolutions during each cycle of endwise reciprocation of a needle 33which cooperates therewith in the formation of stitches passing througha needle hole 34 in the throat plate.

The rotary hook of this invention has an upwardly open cuprshaped formincluding a rim 38 having an upwardly extending bearing shoulder 39. Therim is also formed with an annular inwardly extending bearing rib 40having a lateral opening 4lformed at one side with a needle thread loopseizing beak 42. The needle 33 reciprocates in a path which traversesthe plane containing the path of circular movement of the loop seizingbeak 42.

The cup-shaped rotary hook 28 includes a base 43 formed internally withan annular recess 44, a portion of which may extend completely throughthe hook base to provide clearance for the dip of the needle. The recess44 has another function, i.e., to isolate a raised annular boss 45 atthe center of the base. Segments of the edge of the boss 45 arechamfered as at 46 while intervening portions 48 of the peripheral edgeare formed substantially square. This raised boss 45 serves a functionin pulling off and positioning a bobbin thread during sewing asdescribed in greater detail in my copending US Pat. application Ser. No.135,671 filed Apr. 20, 1971 to which reference may be had.

Constrained within the cup-shaped rotary hook is a bobbin case indicatedgenerally at 50. The bobbin case is formed with an upwardly open bobbinaccommodating cavity 51 through the bottom of which a large controlaperture 52 extends. Externally, the bobbin case is formed with abearing flange 53 which rests upon the bearing rib 40 of the rotary hookand is constrained radially against the bearing shoulder 39. The bobbincase flange at one side is slabbed, as at 54, substantially along achord to provide clearance for the path of needle reciprocation betweenthe bobbin case and the rotary hook. Adjacent to the slabbed portion 54the bobbin case flange 53 is also formed with a shallow recess 55 intowhich fits a rotation restraining element 56 secured by a screw 57 tothe machine bed 20. The bobbin case flange 53 substantiallydiametrically opposite the slabbed portion 54 is formed with a recess 58on which a support arm 59 of a thread tensioning spring bracket 60 issecured by a fastening screw 61.

The bobbin case 50 adjacent to the recess 58 in the flange 53 is formedwith a radial opening 80 across which opening the thread tensioningspring bracket 60 spans. A downturned arm 81 on the bracket 60 is alsodisposed in the bobbin case radial opening 80 and provides a mountingsurface against which a bobbin thread tensioning spring 82 is secured bya screw 83. Preferably, the spring 82 is formed with slot 84 in the formof a U-shaped loop separating a tongue 85 through which the securingscrew 83 and a locating pin 86 on the bracket 81 pass. Surrounding thetongue 85 is an outer spring blade portion 87 which frictionally engagesthe bobbin thread against the downturned bracket arm 81 to provide thebobbin thread tension. The downturned arm 81 is formed with athreadentry slot 88 which, as shown in FIGS. 4 and 9 terminates in aneyelet 89 for directing the thread to the spring blade portion 87 of thespring. Below the spring 82, the downturned arm 81 is formed with athread guiding groove 90 from which the bobbin thread leaves the springand proceeds to the stitching point. The tension exerted on the threadby the spring blade portion 87 may be adjusted by regulating thefastening screw 83.

For additional restraint of the bobbin case within the rotary hook, aholddown spring arm 62 which extends from a base plate 63 and a rotationrestraining arm 64 extending from a base plate 65 are provided. Each ofthe base plates 63 and 65 is formed with an aperture 66 for a shoulderedscrew 67 threaded into the machine bed; and each of the base plates isformed with an elongated slot 68 to accommodate the eccentric head 69 ofa locating pin 70 secured by a set screw 71 in the machine bed. Therotation restraining arm 64 is formed with a downturned lip 72 whichabuts a shouldered portion 73 on the support arm 59 of the threadtensioning spring bracket 60.

The base plate 65 is formed with another arm 75 which, as shown in FIGS.5 and 6 extends alongside the slabbed portion 54 of the bobbin casebetween the path of needle reciprocation and the bobbin case. This arm75, acts as a support for the bobbin thread during sewing to hold thebobbin thread away from the path of the loop taker beak 42. The arm 75is formed with a downwardly tapering upper edge 76 which as shown inFIG. 1 extends beneath the level of the path of the hook beak and isjoined at the free extremity by an upwardly projecting tang 77. Thepurpose of the thread tang 77, is to prevent a bobbin thread from beingcarried off the free end of the arm 75. Also formed at the freeextremity of the arm 75 is an outwardly extending thread guard finger 78adapted to project beneath the inwardly extending bearing rib on therotary hook when the base plate 65 is secured in place. The thread guardfinger 78 serves to direct each'needle thread loop manipulated by therotary hook beak completely over the arm and thus prevents the needlethread loops from lassoing the arm 75. It is also the purpose of theoutwardly extending finger 78 to prevent the beginning end of a bobbinthread from accidentally being directed twice to the bobbin threadtensioning spring when a prewound bobbin is inserted into the machine.

Secured in a reception seat formed beneath the bobbin case at the sideopposite the thread tensioning spring 82 is an arcuate thread cammingblade 91 preferably having a curvature coinciding closely with that ofthe boss 45 which projects upwardly within the cup-shaped rotary hook.As shown in FIG. 12 the blade 91 depends below the level of the boss 45and is spaced outwardly thereof to provide thread clearance. A notch 92is formed near one extremity of the blade 91 to limit the influencewhich the blade can exert on the bobbin thread.

Freely rotatable in the bobbin accommodating cavity 51 of the bobbincase is a bobbin indicated generally at 95. The bobbin includes a topflange 96 formed with an outwardly extending slot 97 skewed slightlyfrom a true radial position on the top flange. The bobbin is formed witha bottom flange 98 having a depending boss 99 which fits into thecentral aperture52 of the bobbin case. The boss 99 is formed with anoncircular central aperture 100. As shown in the drawings, the aperture100 may be hexagonal to match the hexagonal extremity 101 of a drivingspindle 102 which is arranged in the hollow loop taker shaft for drivingthe bobbin when it is desired to replenish thread thereon. Between theflanges 96 and 98 of the bobbin a plain cylindrical hub 103 is provided.

The spindle 102 forms a part of the bobbin thread replenishing mechanismof this invention and, more particularly, is included in the deviceindicated generally at 110 in the drawings for selectively rotating thebobbin 95 to wind replenishment thread thereon. As shown in FIGS. 1 and4, the spindle 102 near its lower extremity is formed with an annulargroove 104 in which the opposed spring arm 105 of a friction washer 106are snapped. The friction washer includes an upturned finger 107 whichis accommodated in a notch 108 formed on the underside of the bevel gear29 on theloop taker shaft. By this arrangement the spindle 102 will bedriven with the loop taker by way of the friction coupling between thefriction washer 106 of the spindle 102. Should sufficient resistance tothe turning of the spindle 102 arise, the spindle, may turn freelyrelatively to the washer 106 and a driving relationship will bereinstated only when the resistance to turning drops below the torquenecessary to cause the friction washer to slip on the spindle 102.

Beneath the friction washer 106 on the spindle 102 is positioned a plainwasher 109 and the lateral arm 111 of an angle bracket 112. A springclip 113 seated in an annular notch 114 in the spindle 102 maintains theparts on the spindle. The angle bracket 112 has fastened thereto anupstanding cylindrical guide stud 115 which slides in a guide bore 116formed in the bed 20. A coil spring 117 which is confined in the guidebore 116 bears against the guide stud 115 and biases the bracket 112 andthe spindle 102 downwardly.

The guide stud 115 extends through the angle bracket 112 and is formedbeneath the angle bracket with a tapered cam follower head 118. The camfollower head 118 tracks a cam surface 128 formed on a radial arm 129which projects from a hub 130 secured as by a set screw 131 on the lowerextremity of a fulcrum stud 132 journalled in the machine bed 20. Theradial arm 129 may preferably be formed of a synthetic plastic materialfor quiet cooperation with the cam follower head, in which case the hub130 may be formed as a metallic insert. The fulcrum stud 132 isretainedin the machine bed 20 by a spring clip 133 and above the machine bed hasfastened thereon by a set screw 134 the hub portion 135 of a control arm136. The control arm 136 is formed with a blade 140 which, as shown inFIGS. 1 and 5 through 8, extends over the loop taker 28. A finger griptab 141 is formed to extend upwardly from the blade 140 and serves, aswill be explainedin greater detail below, for manual positioning of thecontrol arm 136. A downturned finger 142 is formed on the control arm136 closely adjacent to the hub 135. A projection 143 which extendsradially outward along the arm 136 from the downturned finger 142 servesas a thread camming instrumentality when the control arm 136 is turnedin a clockwise direction into the position shown in FIGS. 5 through 8and forces any thread which is being carried by the loop seizing beak 42of the loop taker 28 to be introduced to the bobbin thread tensioningspring 87 and to be directed into the bobbin for replenishment of thebobbin thread supply.

As best illustrated in FIGS. and 11, a thread accommodating passagewayis provided between one edge 150 of the bobbin case opening 80 and oneextremity 151 of the bracket 60 which supports the bobbin threadtensioning spring 82. When the control arm passageway. When the controlarm 136 is shifted in a clockwise direction into the solid line positionas shown in FIG. 5, the projection 143 will be disposed adjacent thepassageway between the surfaces 150, 151 as shown in FIG. 10, and needlethread N being manipulated by the loop seizing beak 42 will be urged anddeflected into the thread accommodating passageway.

When it is desired to replenish thread on the bobbin, it is necessaryfor the operator of the sewing machine to detain the free end of threadextending from the eye of the needle 33 above the throat plate 25, andto shift the control arm 136 in a clockwise direction as shown in FIGS.5 through 8 into a position extending over the bobbin 95. When thecontrol arm is shifted in a clockwise direction the cam surface 128,acting upon the cam follower head 118 will elevate the spindle 102causing the hexagonal end 101 of the spindle to enter in drivingrelationship with the noncircular aperture 100 in the bobbin. It is onlynecessary thereafter, for the operator of the machine to initiate thesewing machine drive to cause reciprocation of the needle 33 androtation of the loop taker 28 as if these parts were to be actuated inthe formation of stitches.

On the first dip of the needle both limbs of the needle thread throughthe eye of the needle will depend downwardly through the needle aperture34 in the throat plate, and the loop taker beak 42 will seize thisneedle thread loop as illustrated in FIG. 5. As rotation of the looptaker continues, the seized loop of needle thread will continue to bedrawn out as illustrated in FIG. 6 with both limbs of the seized needlethread loop passing over the downwardly extending finger 78 of the armas clearly shown in FIG. 6. That limb of the seized needle thread loopwhich extends over the bobbin 95, which is the free end of the needlethread loop from the needle eye detained above the throat plate 25, willencounter the projection 143 of the control arm 136 as is best shownin'FIG. 10. The thread limb will be influenced by the projection 143 soas to enter between the surfaces 150, 151, thence into the thread entryslot 88 and finally upon continued rotation of the loop seizing beakinto the position shown in FIG. 7 into the thread eyelet 89. The needlethread at this stage will have, therefore, been introduced between thedownturned arm 81 of the bracket 60 and the blade 87 of the bobbinthread tensioning spring 82 but the thread will not as yet have beenintroduced into the bobbin nor will the thread have been cast loose fromthe loop taker beak and drawn into the thread guiding groove 90.

As rotation of the loop taker beak continues beyond the position shownin FIG. 7 the loop of needle thread will be drawn off the loop takerbeak 42 and depending upon the position in which the bobbin happened tobe when the spindle 102 was elevated, the radial slot 97 in the topflange of the bobbin will be moved past the free end of the needlethread loop which extends from the eyelet 89 over the bobbin and to theneedle aperture 34 in the throat-plate. As the bobbin continues to turnwith the loop taker, the limb of needle thread which enters the bobbinthrough the slot 97 will be wrapped about the hub 103 of the bobbin. Aswrapping of the thread begins the slack will be dissipated in the threadand it will be drawn into the groove 90.

The slot 97 is preferably skewed with respect to a radius of the bobbinso that the limbof needle thread extending to the throat plate will bemoved back and forth across an edge 160 formed on the blade 140 of thecontrol arm 136. An abraiding action of the thread back and forth acrossthe edge 160 will sever the thread limb after just a few rotations ofthe bobbin after which the retained free end of the needle thread may bewithdrawn and discarded. Thereafter, continued rotaproceeds from thepath of reciprocation of the needle downwardly between the bobbin case50 and the loop taker base 43, between the bobbin thread tensioningspring blade 81 and the downturned arm 81 of th bracket 60 and then intothe bobbin.

Referring to FIGS. 2 and 3, the difference between the manner in whichthe. thread is directed to the bobbin during bobbin thread replenishmentwith the present invention as compared with that of prior known devicesis illustrated. In the prior art devices as shown in FIG. 2, wherein theneedle thread is directed immediately from the path of needlereciprocation 'into the space between the bobbin flanges, both limbs ofthread extending from the eye of the needle are held on a level at orabove the level of the loop taker beak which is indicated at 42 in FIG.2. As a result, even a small degree of slack in the thread beingdelivered to the bobbin will cause formation of a loop of the threadlocated directly in the path of the loop seizing beak 42. Since seizureof a needle thread loop after bobbin thread replenishment has begunwould cause thread breakage and disruption of the replenishmentoperation, care had to be taken with the prior art constructionthatbobbin thread would always be wound faster than that minimum rate whichwould permit the formation of a needle thread loop in the path of theloop seizing beak. As a result, an extremely large diameter hub 103' wasrequired in such prior art bobbins and accordingly, the capacity ofthese bobbins commensurate with any given sized loop taker was limited.Referring to FIG. 3 which shows the condition obtained with the presentinvention, the needle thread which is directed to the bobbin duringbobbin thread replenishment extends from the needle eye downwardly wellbeneath the level of the path of the loop seizing beak 42. In the eventthat slack should develop in this needle thread during bobbin threadreplenishment, any loop which might form adjacent to the needle pathwould occur well below the level of the loop seizing beak and no threadloop would be presented for the beak to seize. Consequently, a smalldiameter hub 103 may be provided on the bobbin and slack thread may betolerated during the initial stages of the winding operation withoutobjectionable loop seizure and thread breakage.

When sufficient thread has been wound on the bobbin, the bobbinthreadreplenishing operation may be terminated by shifting the controlarm 136 counterclockwise as viewed in FIG. S'to the dotted linepositionshown in this viewJThe cam surface 128 will shift relatively tothe cam follower head 118 allowing the spring 117 to lower the spindle102 out of driving engagement with the bobbin. If work is inserted onthe throat plate 25 ben'eath the path of needle reciprocation,subsequent operation of the needle and loop taker will result in theformation of lockstitches in a manner which is well knownin the priorart.

Having set forth the nature of this invention, what is claimed hereinis: 1

.1. In a lockstitch sewing machine having acupshaped circularly movingloop taker including a peripheral rim formed witha thread seizing beak,a thread carrying bobbin j ournalled in'said loop taker, and a threadcarrying needle supported for endwise .reciprocating movement in a pathwhich traverses the plane in which the thread seizing beak moves andextends between the loop taker rim and the bobbin, means forreplenishing thread on said bobbin while in said loop taker from threadcarried by said needle including means for directing thread from saidneedle onto said bobbin, bobbin rotating mechanism for winding threadfrom the needle onto the bobbin during circular movement of said looptaker and reciprocatory movement of said needle, and thread guidingmeans effective to constrain the thread leading to the bobbin duringbobbin thread replenishment in a path which extends inside thecup-shaped loop taker and within the plane in which the thread seizingbeak moves so as to prevent the formation of needle thread loops in thepath of the loop taker thread seizing beak while the bobbin thread isbeing replenished.

2. A circularly moving sewing machine loop taker having a cup-shapedbody formed at the rim with an inwardly extending loop seizing beakadapted to cooperate in the formation of lockstitches with a threadcarrying needle which is endwise reciprocatory in a path substantiallyparallel to the axis of movement of said loop taker, a stationary bobbincase journalled in said loop taker and accommodating a thread carryingbobbin therein, means for replenishing thread on said bobbin while inplace in said loop taker from thread carried by said needle comprising aspring element on said bobbin case for applying tension to a threadleading to said bobbin, means on said bobbin case formed with a threadguiding slot for directing a loop of needlethread seized by said looptaker beak to the influence of said spring element, said thread guidingslot being open at one extremity toward which said loop taker beak movescarrying a seized needle thread loop, and being closed at the oppositeextremity, said closed thread guiding slot extremity being positioned sothat the shortest path for that limb of the needle thread loop extendingtherefrom to the path of needle reciprocation occurs within saidcup-shaped loop taker body between the bobbin case and the loop taker,means for directing into the bobbin the other limb of a needle threadloop introduced into said thread guiding slot and a device for rotatingsaid bobbin to wind thread thereon.

3. A circularly moving sewing machine loop taker as set forth in claim 2in which said means for directing said limb of needle thread loop to thebobbin comprises means supporting one flange of said bobbin exteriorlyof said bobbin case, and said exteriorly supported bobbin flange beingformed with a radial slot for accommodating passage into the bobbin ofsaid other limb of needle thread loop.

4. A circularly moving sewing machine loop taker as set forth in claim 3in which said means on said bobbin case formed with a thread guidingslot extends adjacent to a protective shoulder formed on said bobbincase for preventing needle thread loops being manipulated by said loopseizing beak from entering said thread guiding slot, and a threadcamming finger shiftably supported on said sewing machine adjacent tosaid loop taker and having an effective position contiguous to saidprotective shoulder for urging a needle thread loop being manipulated bysaid loop taker beak into said thread guiding slot.

5. A circularly moving sewing machine loop taker as set forth in claim 4in which said thread camming finger is carried by an operator influencedelement shiftably supported adjacent to the loop taker, and in which athread cutting blade is carried by said operator influenced element formovement into a position overlying the radial slot in said bobbin flangewhen said thread camming finger occupies an effective position.

1. In a lockstitch sewing machine having a cup-shaped circularly movingloop taker including a peripheral rim formed with a thread seizing beak,a thread carrying bobbin journalled in said loop taker, and a threadcarrying needle supported for endwise reciprocating movement in a pathwhich traverses the plane in which the thread seizing beak moves andextends between the loop taker rim and the bobbin, means forreplenishing thread on said bobbin while in said loop taker from threadcarried by said needle including means for directing thread from saidneedle onto said bobbin, bobbin rotating mechanism for winding threadfrom the needle onto the bobbin during circular movement of said looptaker and reciprocatory movement of said needle, and thread guidingmeans effective to constrain the thread leading to the bobbin duringbobbin thread replenishment in a path which extends inside thecup-shaped loop taker and within the plane in which the thread seizingbeak moves so as to prevent the formation of needle thread loops in thepath of the loop taker thread seizing beak while the bobbin thread isbeing replenished.
 2. A circularly moving sewing machine loop takerhaving a cup-shaped body formed at the rim with an inwardly extendingloop seizing beak adapted to cooperate in the formation of lockstitcheswith a thread carrying needle which is endwise reciprocatory in a pathsubstantially parallel to the axis of movement of said loop taker, astationary bobbin case journalled in said loop taker and accommodating athread carrying bobbin therein, means for replenishing thread on saidbobbin while in place in said loop taker from thread carried by saidneedle comprising a spring element on said bobbin case for applyingtension to a thread leading to said bobbin, means on said bobbin caseformed with a thread guiding slot for directing a loop of needle threadseized by said loop taker beak to the influence of said spring element,said thread guiding slot being open at one extremity toward which saidloop taker beak moves carrying a seized needle thread loop, and beingclosed at the opposite extremity, said closed thread guiding slotextremity being positioned so that the shortest path for that limb ofthe needle thread loop extending therefrom to the path of needlereciprocation occurs within said cup-shaped loop taker body between thebobbin case and the loop taker, means for directing into the bobbin theother limb of a needle thread loop introduced into said thread guidingslot and a device for rotating said bobbin to wind thread thereon.
 3. Acircularly moving sewing machine loop taker as set forth in claim 2 inwhich said means for directing said limb of needle thread loop to thebobbin comprises means supporting one flange of said bobbin exteriorlyof said bobbin case, and said exteriorly supported bobbin flange beingformed with a radial slot for accommodating passage into the bobbin ofsaid other limb of needle thread loop.
 4. A circularly moving sewingmachine loop taker as set forth in claim 3 in which said means on saidbobbin case formed with a thread guiding slot extends adjacent to aprotective shoulder formed on said bobbin case for preventing needlethread loops being manipulated by said loop seizing beak from enteringsaid thread guiding slot, and a thread camming finger shiftablysupported on said sewing machine adjacent to said loop taker and havingan effective position contiguous to said protective shoulder for urginga needle thread loop being manipulated by said loop taker beak into saidthread guiding slot.
 5. A circularly moving sewing machine loop taker asset forth in claim 4 in which said thread camming finger is carried byan operator influenced element shiftably supported adjacent to the looptaker, and in which a thread cutting blade is carried by said operatorinfluenced element for movement into a position overlying the radialslot in said bobbin flange when said thread camming finger occupies aneffective position.